Human beings are born with a need for belonging and interaction. Cady Heron when entered the high school after home schooling she could not find any place to sit in the room. She had no body to whom she can relate herself. She felt isolated and had a need to incorporate herself in a group. She could not survive alone in the high school.
Jenis and Damein were first people who offered her friendship and she accepted that, even she left her class because she had to confirm with both of them. This conformity was to serve as a first step towards her inclusion in the group.
When Cady joined the group of plastics she changed herself according to their ways because she wanted to be a part of that group.
Many similar examples come in our society and daily life even. Girls have some issues regarding permission to hang out with friends in some cases. When these girls enter in a new institution like universities they are not accepted by groups because they will prove as a hurdle in way of outing and socialization. The girls usually adapt in such cases and begin to socialize to be the part of certain group. Inclusion criteria of the groups are fulfilled to get the membership.
A boy willing to join a group but the groups are very hard working so the boy would have to start working hard to add up to that category. Similar the boys in colleges have specific way of dressing that separates them from others. To be part of them you have to wear jeans or dress pant as per demand.